Whannell's high-tech detective story has plenty of action, but lacks a good mystery.

“Upgrade” is a full feature at the service of single great idea, but you’ve got to give them this much: it is a great idea. A five-minutes-into-the-future story set in a world of self-driving cars and smart homes (they’re so committed to this aesthetic, the pre-title credits are spoken by a comforting female voice-over), it concerns a regular Joe whose body gets a high-tech upgrade so advanced, he can turn it over to his OS and handily win every physical altercation – all the while conveying a mixture of brio and wide-eyed amazement.

Of course, such a gimmick requires some explanation, and there’s plenty (perhaps a bit too much) of that. The recipient of said upgrade is the improbably monikered Grey Trace, and seriously, has anyone ever known another human with either of those names? He’s played by Logan Marshall-Green, who’s something of a poor man’s Tom Hardy. Grey has a lovely and successful wife named Asha (Melanie Vallejo), and the divide between them is simplicity defined: She works in tech, embracing and forwarding the future, while he’s first seen listening to vinyl while working on a muscle car.

Turns out, he restores cars for a living, and invites Asha to come along as he delivers one to billionaire Erin King (Harrison Gilbertson), who takes the opportunity to show off his latest advancement: a tiny, roach-like circuit that he describes as “a new, better brain.” His guests shrug and head home; the car goes nuts on the way, driving them into an accident due to an “error.” (If one thing is made clear by “Upgrade,” several times in fact, it’s that self-driving cars are a bad, bad idea). You can probably guess what happens next – they’re ripped from the car by bad guys, who leave Asha dead and Grey in a wheelchair. But then Erin shows up with a devil’s bargain: let him implant that chip we were so conveniently introduced to early in the film, and Grey will be able to walk again. The bitter, grieving husband resists a bit, but ultimately doesn’t put up much of a fight; he gets on his feet, and then gets to work.

So it’s a high-tech detective story, but with a twist: Grey is getting communication and commentary from “STEM,” the system operating his disabled body. He first hears STEM as a voice in his head, which he doesn’t much need during the inevitable physical altercations with bad guys – “You’ll need to be a little faster, Grey,” STEM advises, unhelpfully. But the system can “temporarily block your pain receptors,” which comes in handy; even better, with permission, STEM can operate Grey’s body independently of Grey himself, and that’s when the movie kicks into high gear.

Those action beats are kinetic and ingenious, and director Leigh Whannell (who wrote several “Saw” movies and all of the “Insidious” films, as well as directing the third in that series) stages them with vigor, moving the camera in tandem with his hero, keying off the character’s shock and amusement. There’s something inherently comic about a face that’s entirely removed from what a body is doing, and Whannell wisely leans into the humor; it plays, in spots, like “All of Me” as directed by Gareth Evans. And that’s where the carefully prepared character details come into play – by giving us an analog grease monkey with a digital body, Whannell has created a compact version of the classic buddy-cop dynamic (or maybe something closer to those old “thing with two heads” movies).

Once the gimmick is set, our hero is just knocking over bowling pins until he faces off with his only real opponent: someone who’s wired the same way. In the meantime, Whannell finds some inventive ways to invert its detective story conventions, though as a mystery, it’s no great shakes (it lands where you think it will, and then adds on a couple of unfortunate twists). And there’s a boilerplate feel to the law enforcement elements – the great Betty Gabriel from ”Get Out” is stranded in her thinly-drawn cop role – and its vision of the future, which combine to give the picture a real “Minority Report” vibe (not the movie, the Fox TV knock-off).

“Upgrade” comes from the prolific and budget-minded folks at Blumhouse, and it’s a solid veer into the mid-level sci-fi that’s become so ubiquitous on Netflix these days; contrary to the studio’s customary horror M.O., the gore here exists almost solely in the kills. But they are eye-opening, including a memorable scene where one man kills another with a sneeze (yes, really). Yet one wishes that some of the inventiveness of its set pieces and throwaway flourishes could’ve made their way into the main narrative, which is a too-familiar drag. At the end of the day, it’s the action equivalent of a secondhand musical – you’ll most likely come for the dance scenes, and they’re good enough to wade through the filler.

Grade: C+

“Upgrade” premiered in the Midnight section at the 2018 SXSW Film Festival. It opens theatrically on June 1.